The present invention relates generally to packing containers. More specifically, the present invention relates to a tube package of plastic material including a tubular shell part together with end closures front and back. The invention also relates to a method for the manufacture of tube packages.
The use and manufacture of tube packages made of plastic material have been known for a long time. These packages are generally manufactured so that a seamless tube of plastic material is extruded through a plastic extruder including a circular extruder die, the extruded tube being cut off in suitable lengths. These cut tube portions may be provided with a relatively rigid "tube bracing", also containing a cap which may be of the traditional type with a threaded closure top. This "bracing" of the tubes is obtained in such a manner that one end of the tubes is partly introduced into an injection mould, whereupon a molten plastic is pressed into the mould under pressure so that the space of the mould is filled with plastic which also fuses together with the edge zone of tube part inserted into the mould space. Similarly, the tube can then be filled in a traditional manner through its open end and be closed by transverse sealing along the end.
The manufacture of such plastic tubes is relatively slow, however, and therefore expensive and the tubes are difficult to imprint. The reason for the slowness of the method is that the extrusion of tube for technical reasons can take place only at a few meters per minute and that the injection moulding of the "tube bracing" requires a long cooling time.
The abovementioned inconveniences are overcome by the present invention which is characterized in that the shell part of the tube package consists of a molecular-oriented plastic material which has a longitudinal overlap joint. The rear end closure of the tube is constituted of a flattened and transversely sealed portion of the shell part, and the front end closure is constituted of a curved, shrunk portion of the extension of the shell part. The front part of the shrunk portion is provided with a closed emptying opening.
The invention is also characterized by the method for the manufacture of the tube part which involves longitudinally orienting by stretching an extruded web of acrylonitrile plastics (BAREX). The web is printed with the desired text and decoration, and is then divided by longitudinal cutting lines into a number of partial webs. Each of the partial webs is folded to a tube by cutting the webs into lengths corresponding to a tube packing unit and the longitudinal edges of the partial web lengths are joined to one another by overlap joints. The tube formed is threaded onto a mandrel, and is heated and caused to shrink around the profiled end surface of the mandrel so as to form an emptying opening. A separately manufactured cap portion is welded around the emptying opening, the tube is then filled with contents through its open end and the open end is closed by flattening and sealing.